1 // This is a modification of base32 encoding to support the zbase32 alphabet.
2 // The original piece of software can be found at https://crates.io/crates/base32(v0.4.0)
3 // The original portions of this software are Copyright (c) 2015 The base32 Developers
5 // This file is licensed under either of
6 // Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0) or
7 // MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT) at your option.
10 use crate::prelude::*;
12 /// RFC4648 encoding table
13 const RFC4648_ALPHABET: &'static [u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
15 /// RFC4648 decoding table
16 const RFC4648_INV_ALPHABET: [i8; 43] = [
17 -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8,
18 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
21 /// Alphabet used for encoding and decoding.
22 #[derive(Copy, Clone)]
26 /// Whether to use padding.
32 /// Encode bytes into a base32 string.
33 pub fn encode(&self, data: &[u8]) -> String {
34 // output_length is calculated as follows:
35 // / 5 divides the data length by the number of bits per chunk (5),
36 // * 8 multiplies the result by the number of characters per chunk (8).
37 // + 4 rounds up to the nearest character.
38 let output_length = (data.len() * 8 + 4) / 5;
39 let mut ret = match self {
40 Self::RFC4648 { padding } => {
41 let mut ret = Self::encode_data(data, RFC4648_ALPHABET);
44 for i in output_length..len {
48 return String::from_utf8(ret).expect("Invalid UTF-8");
53 ret.truncate(output_length);
56 assert_eq!(ret.capacity(), (data.len() + 4) / 5 * 8);
58 String::from_utf8(ret).expect("Invalid UTF-8")
61 /// Decode a base32 string into a byte vector.
62 pub fn decode(&self, data: &str) -> Result<Vec<u8>, ()> {
63 let data = data.as_bytes();
64 let (data, alphabet) = match self {
65 Self::RFC4648 { padding } => {
66 let mut unpadded_data_length = data.len();
68 if data.len() % 8 != 0 { return Err(()); }
69 data.iter().rev().take(6).for_each(|&c| {
71 unpadded_data_length -= 1;
75 (&data[..unpadded_data_length], RFC4648_INV_ALPHABET)
78 // If the string has more characters than are required to alphabet_encode the number of bytes
79 // decodable, treat the string as invalid.
80 match data.len() % 8 { 1|3|6 => return Err(()), _ => {} }
81 Ok(Self::decode_data(data, alphabet)?)
84 /// Encode a byte slice into a base32 string.
85 fn encode_data(data: &[u8], alphabet: &'static [u8]) -> Vec<u8> {
86 // cap is calculated as follows:
87 // / 5 divides the data length by the number of bits per chunk (5),
88 // * 8 multiplies the result by the number of characters per chunk (8).
89 // + 4 rounds up to the nearest character.
90 let cap = (data.len() + 4) / 5 * 8;
91 let mut ret = Vec::with_capacity(cap);
92 for chunk in data.chunks(5) {
93 let mut buf = [0u8; 5];
94 for (i, &b) in chunk.iter().enumerate() {
97 ret.push(alphabet[((buf[0] & 0xF8) >> 3) as usize]);
98 ret.push(alphabet[(((buf[0] & 0x07) << 2) | ((buf[1] & 0xC0) >> 6)) as usize]);
99 ret.push(alphabet[((buf[1] & 0x3E) >> 1) as usize]);
100 ret.push(alphabet[(((buf[1] & 0x01) << 4) | ((buf[2] & 0xF0) >> 4)) as usize]);
101 ret.push(alphabet[(((buf[2] & 0x0F) << 1) | (buf[3] >> 7)) as usize]);
102 ret.push(alphabet[((buf[3] & 0x7C) >> 2) as usize]);
103 ret.push(alphabet[(((buf[3] & 0x03) << 3) | ((buf[4] & 0xE0) >> 5)) as usize]);
104 ret.push(alphabet[(buf[4] & 0x1F) as usize]);
107 assert_eq!(ret.capacity(), cap);
112 fn decode_data(data: &[u8], alphabet: [i8; 43]) -> Result<Vec<u8>, ()> {
113 // cap is calculated as follows:
114 // / 8 divides the data length by the number of characters per chunk (8),
115 // * 5 multiplies the result by the number of bits per chunk (5),
116 // + 7 rounds up to the nearest byte.
117 let cap = (data.len() + 7) / 8 * 5;
118 let mut ret = Vec::with_capacity(cap);
119 for chunk in data.chunks(8) {
120 let mut buf = [0u8; 8];
121 for (i, &c) in chunk.iter().enumerate() {
122 match alphabet.get(c.to_ascii_uppercase().wrapping_sub(b'0') as usize) {
123 Some(&-1) | None => return Err(()),
124 Some(&value) => buf[i] = value as u8,
127 ret.push((buf[0] << 3) | (buf[1] >> 2));
128 ret.push((buf[1] << 6) | (buf[2] << 1) | (buf[3] >> 4));
129 ret.push((buf[3] << 4) | (buf[4] >> 1));
130 ret.push((buf[4] << 7) | (buf[5] << 2) | (buf[6] >> 3));
131 ret.push((buf[6] << 5) | buf[7]);
133 let output_length = data.len() * 5 / 8;
134 for c in ret.drain(output_length..) {
136 // If the original string had any bits set at positions outside of the encoded data,
137 // treat the string as invalid.
142 // Check that our capacity calculation doesn't under-shoot in fuzzing
144 assert_eq!(ret.capacity(), cap);
153 const RFC4648_NON_PADDED_TEST_VECTORS: &[(&[u8], &[u8])] = &[
154 (&[0xF8, 0x3E, 0x7F, 0x83, 0xE7], b"7A7H7A7H"),
155 (&[0x77, 0xC1, 0xF7, 0x7C, 0x1F], b"O7A7O7A7"),
156 (&[0xF8, 0x3E, 0x7F, 0x83, 0xE7], b"7A7H7A7H"),
157 (&[0x77, 0xC1, 0xF7, 0x7C, 0x1F], b"O7A7O7A7"),
160 const RFC4648_TEST_VECTORS: &[(&[u8], &str)] = &[
164 (b"foo", "MZXW6==="),
165 (b"foob", "MZXW6YQ="),
166 (b"fooba", "MZXW6YTB"),
167 (b"foobar", "MZXW6YTBOI======"),
168 (&[0xF8, 0x3E, 0x7F, 0x83], "7A7H7AY="),
172 fn test_rfc4648_encode() {
173 for (input, encoded) in RFC4648_TEST_VECTORS {
174 assert_eq!(&Alphabet::RFC4648 { padding: true }.encode(input), encoded);
177 for (input, encoded) in RFC4648_NON_PADDED_TEST_VECTORS {
178 assert_eq!(&Alphabet::RFC4648 { padding: false }.encode(input).as_bytes(), encoded);
183 fn test_rfc4648_decode() {
184 for (input, encoded) in RFC4648_TEST_VECTORS {
185 let res = &Alphabet::RFC4648 { padding: true }.decode(encoded).unwrap();
186 assert_eq!(&res[..], &input[..]);
189 for (input, encoded) in RFC4648_NON_PADDED_TEST_VECTORS {
190 let res = &Alphabet::RFC4648 { padding: false }.decode(std::str::from_utf8(encoded).unwrap()).unwrap();
191 assert_eq!(&res[..], &input[..]);
197 let num_padding = [0, 6, 4, 3, 1];
199 let encoded = Alphabet::RFC4648 { padding: true }.encode(
200 (0..(i as u8)).collect::<Vec<u8>>().as_ref()
202 assert_eq!(encoded.len(), 8);
203 for j in 0..(num_padding[i % 5]) {
204 assert_eq!(encoded.as_bytes()[encoded.len() - j - 1], b'=');
206 for j in 0..(8 - num_padding[i % 5]) {
207 assert!(encoded.as_bytes()[j] != b'=');
213 fn test_decode_rfc4648_errors() {
214 assert!(Alphabet::RFC4648 { padding: false }.decode("abc2def===").is_err()); // Invalid char because padding is disabled
215 assert!(Alphabet::RFC4648 { padding: true }.decode("abc2def===").is_err()); // Invalid length
216 assert!(Alphabet::RFC4648 { padding: true }.decode("MZX=6YTB").is_err()); // Invalid char